System for salvaging submerged objects



March 17, 1970 R. J. STRANGE 3,500,785

v SYSTEM FOR SALVAGING SUBMERGED OBJECTS Filed Feb. 5, 1968 .4 Sheets-Sheet 1 INVENTOR. ROBERT J. STRANGE WIJWWL? ATTORNEYS 4- MMMWM March 17,' 1970 R. J. STRANGE 3,500,735

' SYSTEM FOR SALVAGING SUBMERGE'D OBJECTS Filed Feb. 5, 1968 .4 Sheets-Sheet 2 Y. '7"; E A A A I 9191;919:9191; 1 0. QAQAQQAQAQAQQA FIG. 3

INVENTOR. ROBERT J. STRANGE MMmmmna/wmm" Mew? ATTORNEYS March 17, 1970 R; J. STRANGE 3,500,785

SYSTEM FOR SALVAGING SUBMERGED OBJECTS Filed Feb. 5, 1968 .4 Sheets-Sheet 3 INVENTOR.

I H I ROBERT J. STRANGE M14, M11,- M @MW ATTORNE-YS v R. J. STRANGE SYSTEM FOR SALVAGING SUBMERGED OBJECTS March 17, 1970 .4 Sheets-Sheet 4 Filed Feb. 5, 1968 FIG. 5

INVENTOR. ROBERT J. STRANGE .BMMMWBMM Wa d ATTOR NE-YS United States Patent 3,500,785 SYSTEM FOR SALVAGING SUBMERGED OBJECTS Robert J. Strange, 1270 Gibbs Ave., St. Paul, Minn. 55108 Filed Feb. 5, 1968, Ser. No. 703,106

Int. Cl. B63c 7/12 US. Cl. 114-50 13 Claims ABSTRACT OF THE DISCLOSURE A system and method for salvaging submerged marine vessels and other submerged objects, according to which a plurality of flexible inflatable containers are disposed in accessible compartments of the sunken object and/or secured to its exterior and inflated until the object is buoyant. The submerged object is permitted to rise progressively in controlled predetermined increments. Rapid upward acceleration of the object due to rapid expansion of the volume of gas in the inflated containers is prevented. When the object reaches the limit of each controlled incremental rise, the buoyancy of the containers is reduced by bleeding air therefrom or otherwise, while still maintatining the object buoyant. Then the submerged object is permitted to rise a further predetermined amount, and the buoyancy of the inflated containers is again reduced. This is repeated until the object is surfaced. This invention relates to a relatively simple and relatively inexpensive system and method for economically salvaging submerged marine vessels and other objects. Hundreds or ships have been sunk, as the result of storms or collisions or otherwise, through the ages. Although many of these ships may contain valuable cargo or fittings and may themselves have considerable salvage value, relatively few sunken ships have been recovered because the great cost of salvaging usually exceeds the value of the ship and it contents. Similarly, many aircraft have been lost due to ditching and off-shore radar and drilling platforms have been damaged and sunk.

Numerous techniques for raising sunken vessels and similar objects have been proposed in the past. With particular reference to submerged ships: (1) Openings in the vessel may be sealed and water forced out as air is pumped in, or water is displaced by air pumped into dome-like areas near ceilings, in holds, and the like. (2) Cables may be passed under the ship and attached to ballasted barges. The barges may be pumped out raising the ship a few feet. The ships are moved toward land until the submerged vessel again touches bottom. The cables are shortened and the process repeated until the submerged vessel is afloat. (3) Large rubber bag may be introduced into the holds and staterooms and the like and then inflated forcing the water out. (4) Plastic foam may be formed in place within the sunken ship displacing the water until gradually the ship rises. (5) Lightweight rigid plastic balls capable of withstanding tremendous pressure may be introduced into open spaces within the vessel. (6) Metal pontoons may be attached to the vessel and filled with air.

All of these proposed salvaging methods have serious drawbacks. Most are prohibitively expensive. Where the ship is to be raised a a result of air pumped into a closed chamber, whether it be part of the vessel, an inflatable bag, a pontoon or tank, or the like, one of the main obstacles is control of the rate of rise. Unless the total gas volume in the ship is reduced as the vessel rises, the vessel will gain momentum and explode as the result of rapid uncontrolled expansion of the gas. This may occur before surfacing or the vessel may burst out of the water and crash to the surface doing great damage.

It is the principal object of the present invention to provide a relatively simple and relatively inexpensive means by which the obstacles of the prior art may be overcome and a vessel or other object may be salvaged economically. In its broadest terms, the system and method of the present invention involves rendering a submerged vessel or other object buoyant and then controlling the rate of rise of the buoyant vessel or other object. For convenience, the invention will be described and illustrated with reference to ships, but it will be understood that the same principles are equally applicable to other submerged objects. A plurality of flexible light weight inexpensive inflatable plastic containers are disposed in accessible compartments of the sunken vessel or secured to the exterior of the vessel, or both. Enough of these inflatable containers are provided to render the vessel buoyant when they are inflated with air or other gas. When the inflatable containers are filled with gas sulficient to render the sunken vessel buoyant, the vessel is permitted to rise a predetermined limited short distance, but not so far that the vessel gain-s uncontrollable momentum as a result of reduced pressure and gas expansion. The buoyancy of the containers is then reduced by bleeding air from them, or otherwise, until they are just barely able to maintain the vessel buoyant. Then the vessel buoyant when they are inflated with air or other gas. limited distance. The buoyancy of the containers is again reduced and the procedure is repeated a necessary to raise the vessel in stages until the vessel is surfaced.

The rate of rise of the vessel may be controlled in either of two principal ways: (a) The vessel may be connected to heavy-duty anchors by means of securing or tethering lines held down by, but movable and extendible with respect to, the anchors. By extending the lines relative to the anchors a predetermined limited amount after the vessel is made buoyant, the vessel will rise a corresponding short distance. After the buoyancy is reduced by bleeding gas from the containers the lines are extended a further predetermined limited amount to permit the vessel to rise a corresponding short distance. b) The vessel may be connected by lines to a plurality of balloon-like inflated containers floating near the surface of the water. When these containers rise to the surface, the lifting of the vessel stops. While some of the containers maintain the vessel buoyant, other inflatable containers are fastened to the lines a predetermined distance below the first, say 10 feet or so. When these other containers are inflated, the vessel rises that predetermined distance and the first containers may then be refastened to the lines to repeat the lifting a further short distance. In some instances, a combination of the two principal systems of controlling rise of the vessel may be used.

The invention is illustrated in the accompanying drawings in which corresponding parts are identified by the same numerals and in which:

FIGURE 1 is a schematic representation of one form of system for raising a submerged vessel according to the present invention showing a vessel just after it has been lifted from the ocean floor;

FIGURE 2 is a vertical section illustrating one form of hoist vessel which is economical to build and which may optionallly be used in conjunction with the system of the present invention;

FIGURE 3 is a top plan view of the vessel of FIGURE 2 shown with part of the decking broken away to reveal internal construction;

FIGURE 4 is a vertical section showing one form of simple heavy-duty anchor which may be used in conjunction with the systems of the present invention;

FIGURE 5 is a schematic representation of a modified form of system for recovering a submerged vessel lying at a point near the shore or elsewhere where the floor of the body of water falls away rapidly in a sharp incline;

FIGURE 6 is a plan View of an alternative form of heavy-duty anchor means useful for general duty but especially adapted for use on a sloping sea floor;

FIGURE 7 is a schematic representation of a still further alternative form of system for raising submerged vessels according to the present invention;

FIGURE 8 is an elevation of one form of heavy-duty lifting harness for enclosing an inflatable container to be attached to the outside of a submerged object; and

FIGURES 9, 10 and 11 are fragmentary sections on an enlarged scale showing details of the harness of FIG- URE 8.

Referring now to the drawings, and particularly to FIGURE 1, there is shown a submerged vessel, indicated generally at 10, resting in the sea or ocean water 11, between the bed 12 and surface 13. The vessel 10 is shown in a position of buoyancy after release from the ocean bed. The vessel 10 is anchored in this position by means of a plurality of heavy-duty anchor means, indicated generally at 14. A plurality of lines, of which two indicated at 15 and 16 are shown, extend from a surface service vessel, indicated generally at 17, through eyes 18 of the anchors 14, and thence to points of attachment to vessel 10. The lines are slidable with respect to the anchors so that, as line is played out from winches 19 on the service vessel in short increments of predetermined length, the segment of line between the anchors and the vessel 10 may increase while the segment of line between the anchors and the service vessel remain substantially constant.

The vessel 10 is made buoyant by means of a plurality of inflatable containers 20 and 21. A portion of the hull of vessel 10 is shown broken away to reveal an interior placed inflatable container 20 occupying most of the space in a hold 22 or similar compartment in the vessel. Con ainer 20 is made of relatively light gauge air-impermeable plastic sheet material. For ease of construction of each container of a size and shape such that it will substantially fill the compartment for which it is designed upon inflation, the material should be heat sealable. It may be relatively inelastic because it i intended to be inflated only within predetermined limits established by the size of the compartment in which it is to be located.

Because of its ready availability in wide widths, good heat-scalability, ease with which it may be worked and low cost, polyethylene is a preferred film material. However, other materials available for use in forming a relatively thin, impermeable, smooth, tough, pliable, membranous, relatively inextensible, sealable synthetic resinous film include butadiene-acrylonitrile copolymers, vinyl choride-vinyidene chloride copolymers, rubber hydrochloride, other vinyl chloride and vinylidene chloride polymers and copolymers, butadiene-styrene copolymers, polyester such as Myla and the like.

The inflatable containers are formed easily from large sheets of the plastic film cut to appropriate size and shape and then sealed, by heat or with adhesive or tape or otherwise. The container is formed with gas inlets, valves, etc., sealed into the container walls suitably located. For example, when the container is to be inflated with air, the inlet tube or other entry is located so as to be readily accessible when the container is installed in a compartment in a submerged vessel so that it may be inflated. When the container is to be inflated, for example, with carbon dioxide from a Dry Ice canister, the inlet should also be accessible. The container is fitted with a pressure relief valve. When intended to be manually operated by a diver, this is also located so as to be accessible after the container 20 is inflated, so as to relieve pressure within the container periodically as the vessel is being raised. When an automatic pressure release valve is used, accessibility is less important.

If the compartment in which an inflatable container is to be placed has sharp edges or projections such a corners of furniture; furniture legs; heating, lighting or plumbing fixtures; or the like which might pierce or tear the plastic film, the container is desirably enclosed in a tough fabric envelope, such as canvas. Such an envelope may be formed by cutting sheets of canvas to generally the same size and shape as the plastic film from which the container is formed, only slightly larger, and then stitching the edges together over the heat-sealed plastic edges. Not only is the plastic container protected against sharp object but also against ballooning out through open doorways, portholes, etc.

The inflatable containers 20 are placed in all of those interior compartments of the vessel which are most readily accessible to the divers who must place the containers and gain access to them for inflation for initial buoyancy and partial deflation as the vessel rises. Because of this limitation, only the more readily accessible compartments, such as the lounges and other public rooms, foyers, staircases, cargo holds, enclosed promenade decks, and the like are available.

If it is difficult for any reason upon inflation of containers 20 to displace sufficient water to render the submerged vessel buoyant, then auxiliary buoyancy means, such as inflatable containers 21, may be utilized. Containers 21 are similar to containers 20 in that they are formed fro-m the same or similar lightweight sealable plastic film material. Each inflatable container 21 is partially enclosed in a harness such as canopy 23. A plurality of shroud lines 24 are connected to the periphery of the canopy and extend to a common fitting 25 by which the canopy and partially enclosed inflatable bag are securely attached to some portion of the hull or superstructure of the submerged vessel.

The canopy may be formed, for example, from canvas, fishnetting, or similar material strong enough to restrain the inflatable container 21. Similarly, the lines 24 and fitting 25 must be strong enough to restrain the inflatable container 21 to prevent it from breaking away from the submerged vessel as it is inflated and as it becomes more buoyant as the vessel raises. For easy access, the pressure release means for each container is desirably located at 26 at the top of the canopy when the enclosed container is inflated.

Suflicient auxiliary inflatable containers 21 are provided so that, in combination with the interior inflatable containers 20, they displace in the aggregate enough water to render the submerged vessel 10 buoyant. Under some circumstances, it is desirable that the required buoyancy be achieved by use of exterior inflatable containers 21 only, without the use of any inside compartment containers 20. In other instances where compartments of ample displacement capacity are readily accessible, no auxiliary buoyancy means may be necessary.

In most instances, the volume of water which must be displaced from the vessel in order to render the vessel buoyant can be estimated with reasonable accuracy. Then the required number of inflatable containers, both interior and exterior, necessary to provide this displacement volume upon inflation, can also be determined with reasonable precision. According to one embodiment of the invention, while the submerged vessel still rests at the bottom of the body of water, anchors of sufficient size, weight and number to control the vessel are lowered in the near proximity of the submerged vessel and lines are extended from the vessel to the anchors, and optionally to a service vessel 17 at the surface. The length of line between the vessel and anchor means is adjustable in increments. Initially, it is slack enough to permit the vessel to rise some predetermined limited distance from the bottom, such as 10 or 15 feet, for example.

Once the submerged vessel 10 is secured to the anchors, the inflatable containers are filled with gas to their approximate designed capacities. The containers may be inflated, for example, by compressed air or air pumped from the service vessel 17, or by carbon dioxide released by sublimation from Dry Ice from a canister connected to the container. Initially, the containers are desirably inflated to the point where the vessel is just buoyant such that it barely floats at the ends of its tethering lines but without exerting great force on those lines. Then a small amount of additional gas is introduced so that the vessel begins to rise to the limits of its tethering lines.

As the submerged vessel begins to rise and water pressure on the exterior of the inflated containers decreases due to diminished water depth, the confined gas expands increasing the interior pressure, the volume of water displaced and the buoyancy of the vessel. The resulting acceleration of the rate of rise of the submerged vessel is maintained under control because of the limited rise permitted because of the limited slack in the lines between vessel and anchor means.

When the vessel reaches the limit of its rise as permitted by its tethering lines, then the pressure within each of the inflated containers is released to the point where the vessel is once again just barely buoyant, but this time at its new level above the bed of the body of water from which it has been lifted. Then each of the tethering lines is extended a predetermined limited amount between the vessel and the anchor means. This creates new slack in the lines. Again the buoyancy of the submerged vessel is increased enough to initiate further rise of the vessel to the new limits imposed by the lengthened tethering lines.

In the case of a vessel lying in a position as illustrated in FIGURE 1 with the stern lower than the bow, the stern lines may be lengthened in increments while the bow lines remain constant until the submerged vessel is on approximately even keel. Thereafter, all of the lines are lengthened uniformly so as to raise the ship in its level position.

Where a surface service vessel 17 is utilized, then the tethering lines may be lengthened by virtue of winches 19 playing out a predetermined length of line. Such a service vessel is not essential, however. Instead, the lines may be lengthened manually by divers, or otherwise. Regardless of how the tethering lines are lengthened, the submerged vessel is permitted to ease up gradually in limited progressive increments by repeating the described process until the vessel is surfaced. Then the water within the vessel may be pumped out and the vessel refloated. Because of the use of relatively low cost inflatable containers, relatively inexpensive heavy-duty anchoring means and relatively inexpensive service vessels, salvage opera tions may be carried out inexpensively and economically.

Referring now to FIGURES 2 and 3, there is shown one form of easily constructed relatively inexpensive service vessel which may be used to assist in the salvaging of submerged vessels. The hull 27 is a simple platform composed of a plurality of sealed metal barrels or drums 28 secured together by welding or by means of chains or cables and enclosed in a framework or housing 29, the upper surface of which supports a deck 30. The hull desirably includes a central vertical hoist opening 31 through which divers, material, hoist lines, etc. may be lowered and raised during the salvaging operation. A plurality of heavy-duty sheaves 32 are provided in the opening 31 to guide tethering lines from hoist means 19, etc.

A superstructure 33, which may be in the form of a reinforced steel frame building, is desirably mounted on the deck over the central opening 31. Means, such as hook 34 for suspending sheaves, etc., are desirably mounted over the central opening 31 to facilitate the salvaging operations. Auxiliary equipment such as generators, air pumps and compressors, power means for the hoists, and the like may be located within the superstructure.

A weight of about two hundred tons would be required to sink a pontoon vessel constructed according to the illustrated design and including nine hundred 55-gallon drums. Because such drums are readily available in second hand condition at nominal prices, a pontoon vessel may be built with relatively unskilled labor at relatively low cost. Generally speaking, a service vessel should be able to withstand the rigors and forces of at least about type 5 seas.

Referring to FIGURE 4, there is shown one form of relatively simple inexpensive hanger hook anchor means, indicated generally at 14, which is useful in carrying out salvage operations according to the system of the present invention. The anchor includes a frame which comprises a large diameter circular disk 35, preferably concave, to the periphery of which are welded or otherwise attached the ends of a plurality of elongated steel plate stringers 36 extending inwardly and upwardly to a large eye bolt 18, to which the opposite ends are welded. The stringers 36 are evenly spaced about the periphery of disk 35 and eye 18 lies on the approximate longitudinal axis of the anchor means. The lower end of a heavy cylindrical steel shell 37 is secured to the periphery of disk 35, preferably detachably as by pins or light shearable welds.

In use, the anchor means 14 is first lowered to the floor of the body of water adjacent the submerged vessel to be raised. Thereafter, high density ballast is placed in the anchor means within the shell until it is filled. This may be done through a large diameter conduit from the service vessel at the surface. Upon completion of the salvaging operation, the shell 37 is detached from the disk 35 of the anchor frame and raised relative to the frame. This permits the ballast contained within the tubular shell to flow out to the sea or ocean floor so as to substantially decrease the gross weight of the anchor means to permit withdrawal.

By way of example, the anchor of the naval aircraft carrier, U.S.S. Midway, a 60,000 ton vessel, weighs 29,000 pounds. An anchor constructed as illustrated, with a diameter of ten feet and a height of eleven feet ballasted with concrete rubble whose density is about pounds per cubic foot, will have a gross weight of about 164,000 pounds. An anchor of the same size loaded with lead, whose density is 687 pounds per cubic foot, will weigh 595,000 pounds. Such an anchor may be constructed relatively inexpensively using as disk 35 a standard steel inch thick bulkhead as used in making steel tanks. Similarly, shell 37 may be formed from steel tank drum stock of inch thickness and stringers 36 may be formed from six inch by 4 inch steel plates, all of which are readily available.

Referring now to FIGURE 5, there is shown a submerged vessel 10A which lies on the bed 12A of a body of water relatively close to the shore 38 so that the bottom falls off rapidly in a relatively deep incline. Such a vessel may be salvaged in the manner already described in connection with the system illustrated schematically in FIGURE 1, using inflatable containers located within accessible compartments of the vessel or suspended from the outside of the vessel or both in combination. However, control of the vessel is made difficult because of the slope of the floor 12A. Heavy-duty anchor means of the type shown in FIGURES 1 and 4 tend to slide down the inclined floor of the body of water. For this reason, an alternative form of heavy-duty anchor means is provided for use on sloping surfaces.

As best seen in FIGURE 6, this form of anchor means, indicated generally at 39, includes a pluralty of drums or barrels 40, each of which is filled with concrete in which are embedded one or more eye bolts 41, 42 and 43. The anchor is assembled at the salvaging site to meet the requirements dictated by the conditions which are present. Adjacent drums 40 are flexibly linked together by means of short lengths of chain or cable 44 in side-by-side and end-to-end relation. As many drums are linked together as are needed to supply the required gross anchor weight. The assembled anchor resembles a loose net or open work blanket which lies flat on the bed 12A of the body of water hugging the surface and remaining in place in spite of the incline of the surface.

Although especially adapted for use on sloping surfaces, the anchor means 39 has general utility under all conditions. When a force is applied to the lead drum tending to lift it from the sea floor the following drums are subjected to a dragging force. The lips on the lead edges of the drums act like digging buckets and tend to dig into the soft soil or silt of the sea floor creating a drag force of large magnitude making dragging of the anchor difficult. A large network composed of many individual drums flexibly linked together can be assembled at the site to adapt to whatever conditions may be found.

Referring now to FIGURE 7, there is shown schematically a further alternative system by which submerged vessels may be salvaged using lightweight inflatable plastic containers suspended from the exterior of the submerged vessel. This system is best adapted for used for salvaging small vessels or where access by divers is diflicult or where the submerged vessel lies in relatively shallow water. According to this alternative method, a plurality of inflatable plastic containers 21 partially enclosed in a canopy 23 are connected by means of shroud lines 24 to a hoist line 45 which extends to the submerged vessel B where it is secured to the hull or superstructure of the vessel. Hoist lines are of such a length that the containers 21 when inflated lie a predetermined relatively short distance below the surface 13 of the body of water in which the vessel 10B is submerged. The vessel may be anchored by anchor means 14 and tethering lines 46 although this is not always necessary. While the position of the vessel is controlled by the anchor means, the containers are inflated sufficiently to render the vessel buoyant. The tethering lines are temporarily released from the anchor means and the vessel rises the predetermined short distance by which the inflated containers 21 lay beneath the water surface 13. When the inflated containers emerge from the water at the surface, they displace less water and are less buoyant, while remaining buoyant enough to support the vessel 10B lifted from the floor 12. While the ship is thus supported off the bed of the body of water, it is again tethered to the anchor means by lines 46 and a second set of inflatable containers 21 is attached to the hoist lines 45 a predetermined distance below the point of attachment of the first set and inflated. The first set of containers may then be removed from the hoist lines and the vessel raised a further increment. The procedure is repeated until the vessel is surfaced.

Under many circumstances adequate control over the lifting rate of the submerged vessel may be exercised without the use of any anchoring means whatsoever. Hoist lines 45 are desirably provided with spaced apart fittings, at intervals of about every ten feet, for example, to which the balloon-like inflatable containers may be attached. The limit of rise is imposed by the surfacing of the inflated containers and reduction in their buoyancy due to d1s placement of a lesser volume of water. The increment of rise is determined by the spacing of the connecting fittings along the hoist lines. Chains may be used as hoist lines and the inflatable containers attached to appropriately spaced apart links.

Referring now to FIGURES 8 through 11, there is shown one preferred form of harness or sheath to enclose an inflatable container for attachment to the outside of a submerged object for salvage. According to this form of construction containers capable of lifting as much as 100 tons or more each are possible. The canopy, indicated generally at 23, is desirably made from canvas or similar sturdy fabric. It is provided at its apex end with a central circular opening. A plurality of web straps 50 radiate out from the central opening to the canopy skirt. A strong ring, such as a high tensile steel ring 51 is disposed within the central opening. Each strap 50 preferably extends around ring 51 in a loop. The opposite end of each strap 50 extends a short distance beyond the canopy skirt and passes in a loop through a ring fitting 52 to which shroud lines 24 are connected.

Each strap is of double thickness, its ends being overlapped and stitched together to form a continuous loop which in turn is stitched to the canopy. Desirably, one side of each strap extends along the outside of the canopy and the other extends along the inside of the canopy as shown, although this is not essential. The strap 50 is desirably formed from heavy-duty material such as high tensile nylon webbing, or the like. If desired or necessary, the canopy can be additionally reinforced by the means of cross webbing 53 extending between adjacent straps 50 and secured thereto. For maximum strength, the shroud lines 24 desirably extend from one fitting 52 at the skirt of the canopy through fitting 25 and thence to the corresponding fitting 52 diametrically opposite from the first.

The inflatable lightweight plastic container is enclosed within the canopy and shroud lines. This form of construction allows even distribution of the loading force put on the inflated container and its enclosing canopy. The materials are selected to meet load requirements. High tensile nylon rope or cables or steel cables are readily available. Similarly, high tensile webbing of nylon and other fibers are readily available. It is desirably fitted with an exhaust valve 26 extending through the ring 51 at the apex of the canopy. The inflatable container is also desirably fitted with a pressure relief valve 53, which is desirably of a self-operating bellows type. The container is also provided with a gas inlet valve 54. The inflating gas may be air pumped into the container. Alternatively, a Dry Ice canister 55 may be attached to the gas inlet.

Such a canister consists, for example, of a closed housing of aluminum or the like of suflicient strength to withstand the water depths in which it is to be used and having an exit valve adapted to mate with the gas inlet valve of the inflatable container. The housing is partially filled with crushed Dry Ice and also contains a rupturable film bag of acetone. The canister is fitted with a plunger whose stem extends through the canister wall to an outside handle for manual operation. By pulling on the plunger handle after the canister has been connected to an inflatable container, a driver may rupture the acetone bag causing rapid evolution of carbon dioxide due to sublimation of the Dry Ice.

I claim as my invention:

1. A system for salvaging submerged marine objects which comprises in combination:

(A) a plurality of flexible inflatable containers disposed in water displacement relationship with said submerged object,

(B) means for inflating said containers,

(C) means for controlling the rise of said submerged object in response to the buoyancy of the inflated containers in predetermined increments, said means comprising:

(1) heavy duty anchor means on the bed of the body of water adjacent to the submerged object,

(2) lines extending from the submerged object to said anchor means,

(3) said lines being extendible relative to said anchors, the length of line between said anchor and said submerged object increasing as said object rises, and

(D) means for partially and progressively reducing the buoyancy of said container in increments as said object rises and gas within said containers expands.

2. A system according to claim 1 further characterized in that the submerged object has internal compartments and said flexible inflatable containers are disposed in at least some of the compartments of the submerged object,

each of said containers corresponding in size and shape to the compartment in which it is disposed, having means for inflation, being capable of substantially filling the compartment when fully inflated, and having means for partial and progressive deflation.

3. A system according to claim 1 further characterized in that a plurality of flexible inflatable containers are disposed in the body of water above said submerged object, each of said containers being connected to the exterior of said submerged object, said containers being at least partially enclosed within a force distributing sheath and having means for inflation and partial and progressive deflation.

4. A system according to claim 1 further characterized in that each of said anchors comprises:

(A) a large diameter circular steel base,

(B) a plurality of similar relatively narrow elongated steel stringers rigidly secured to said base at spaced intervals about its periphery,

(C) said stringers extending inwardly and diagonally upwardly and being rigidly secured together adjacent their upper ends,

(D) means secured to the upper ends of said stringers at their connection to one another for engaging said lines at spaced intervals along their lengths, and

(E) a cylindrical shell secured to said base and extending upwardly to about said line engaging means.

5. A system according to claim 4 further characterized in that said cylindrical shell is detachably secured to said base.

6. A system according to claim 1 further characterized in that said anchor means comprises:

(A) a plurality of dense weighted cylindrical tanks,

(B) means in the ends of said tanks for flexible end-toend connection of at least some of said tanks, and

(C) means in the sides of at least some of said tanks for side-to-side connection of at least some of said tanks.

7. A system according to claim 1 further characterized in that said inflatable containers are constructed of thin relatively inelastic synthetic resinous sheet material.

8. A system according to claim 2 further characterized in that said inflatable containers are enclosed within a protective envelope of tough fabric, said envelope corresponding in size and shape to the inflatable container and the compartment in which it is disposed.

9. A system according to claim 3 further characterized in that said flexible inflatable container is generally spherical, said force distributing sheath enclosing the container is generally semi-spherical, a plurality of high tensile reinforcing straps extend radially from the apex of said sheath to the edges thereof, and a plurality of high tensile lines extend from the ends of said straps to means for attachment to the submerged object.

10. A method of salvaging submerged marine objects which comprises:

(A) disposing a plurality of flexible inflatable containers in water displacement relationship with the submerged object,

(B) inflating said containers to displace water until the submerged object is buoyant,

(C) controlling the movement of said submerged object to permit it to rise a predetermined limited distance by (1) locating heavy duty anchor means on the bed of the body of water adjacent to the submerged object,

(2) extending lines from said anchor means to the submerged object, and

(3) lengthening said lines a predetermined fixed amount to permit extension of the lines relative to said anchor means to permit controlled limited lifting of said submerged object,

(D) reducing the buoyancy of said containers while still maintaining the object buoyant,

(E) again controlling the movement of the submerged object to permit it to rise a further predetermined limited distance by again lengthening said lines a predetermined fixed amount to permit further controlled limited lifting of the submerged object, and

(F) repeating said last two steps to raise the submerged object in controlled increments until surfaced.

11. A method according to claim 10 further characterized in that at least some of said inflatable containers are disposed in compartments of the submerged object, each of said containers corresponding in size and shape to the compartment in 'which it is disposed and capable of substantially filling the compartment when fully inflated.

12. A method according to claim 10 further characterized in that at least some of said inflatable containers are connected to the exterior of the submerged object to suspend the object when lifted from the bed of the body of Water.

13. A method according to claim 10 further characterized in that the movement of said submerged object is controlled by:

(A) disposing in the body of water above the submerged object just below the surface of the water and connected by lines to said object, a plurality of first inflated containers sufficient to render the submerged object buoyant,

(B) permitting said first inflated containers to lift the submerged object, rising to the surface of the water and thereby partially losing their buoyancy,

(C) While said first containers support the submerged object partially lifted, attaching a plurality of further inflatable containers to the lines connecting said first containers to the submerged object a short predetermined distance below the point of attachment of the first containers and inflating the same,

(D) permitting said further containers to rise to the surface of the water further lifting the submerged object said predetermined distance,

(E) deflating said first containers, detaching and reattaching to said lines a short predetermined distance below said further containers and re-inflating, and

(F) repeating said steps until the submerged vessel is surfaced.

References Cited UNITED STATES PATENTS 1,368,787 2/1921 De Gratf 11453 2,349,480 5/ 1944 Walk 9324 X 2,679,224 5/ 1954 Sturtevant 11454 3,019,754 2/ 1962 Welshausen 114-54 ANDREW H. FARRELL, Primary Examiner US. Cl. X.R. 114-51 UNITED STATES PATENT OFFICE "CERTIFICATE OF CORRECTION Patent No. 3 500 785 Dated March 17 19 70 Inventor(s) Robert J. Stran e It is certified that; error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1 Abstract of the Disclosure should end on line 27 after "faced." Balance of paragraph should constitute first paragraph of specification.

Column 1 line 30 "or" should be "of" Column 2 line 26 "buoyant when they are inflated with air or other gas should be -is again permitted to rise a further predetermined--.

Column 7 line 47 "lines" should be -line- Column 8 line 70 "container" should be containers SIGNED AND SEALED JUL28I970 Attcat:

Edward M. memb r. I mrm 2:. sum, .18. Anesting Officer c' missione'r of Patent! 

